Abstract
ATP-dependent DNA ligase prepared from ascites hepatoma of rat was markedly inhibited by bleomycin at the low concentration. The inhibition was observed in the absence of a thiol compound. However, the degree of inhibition was increased by addition of mercaptoethanol to the reaction mixture. The principal mechanism of inhibition was found to involve the strand scission of DNA which was not repaired by the ligase. The inhibition at rather low concentration of bleomycin suggested that this antibiotic might affect the joining of DNA by binding to DNA strand or by interaction with the enzyme.
